Process for forming magnetic elements



Sept. 16, 1930. A P, WARNER 1,775,981

PROCESS FOR FORMING MAGNETIC ELEMENTS Filed Jan. 1l, 1929 Illllllllllm:

Patented Sept. 16, 1930 4 UNITED STATES PATENT OFFICE ARTHUR P. WARNER,OF BELOIT, WISCONSIN, ASSIGNOR TO WARNER ELECTRIC BRAKE l CORPORATION,OF SOUTH BELOIT, ILLINOIS, A CORPORATION OF ILLINOIS PROCESS FOR EORMINGMAGNETIC ELEMENTS Application filed January 11, 1929. Serial No.331,902.

`This invention relates to improvements in the formation ofelectromagnetic elements and more particularly to elements which areused in electromagnetic friction devices such 5 as clutches and brakes.

In ordinary magnetic friction devices wherein the coacting surfaces ofthe magnet andl its armature are brought into gripping engagement bymagnetic attraction, residual magnetism of considerable Ymagnitude develops upon the interruption of the energizing circuit. This prolongsthe adherence of the elements thereby preventing release of the clutchor brake as the case may be.

One way to eliminate this undesirable effect is to--provide anon-magnetic gap of fixed reluctance in the magnetic circuit. @wing tothe small dimension of the gap it is customary to make the magneticelement in two 2c parts between which is inserted a thin sheet of brassor other non-magnetic material.

This method when employed inthe formation of annular magnetic elementsrequires great'precision in the formation of the rings and in securingthemrtogethe-r in order` to form an element having the desired rigidity.As a result the elements of this character heretofore constructed havebeen unduly costly.

rIhe primary object of the present invention is to simplify theformation ofvmagnetic elements of the above character by providing anovel process for inserting the non-magnetic strip of material betweenthe sections of which the element is composed.

In practicing this improved method two separate magnetic rings areformed of proper dimensions and an adhering coating of nonmagnetic metalis deposited around all or part of the peripheral surface of one of theelements after which the two elements are assembled leaving thenon-magnetic sheet of metal between them.

The invention also aims to provide a novel` Figures l and 2 aresectional views of magnetic elements constructed in accordance with thepresent invention.

Fig. 3 is a fragmentary view of an electromagnetic element illustratingone way of applying the non-magnetic coating thereto.

Fig. 4 is a plan view of a surface of a mag*v netic element partiallycoated.

Fig. 5 is a fragmentary elevational View of a completed magneticelement.

While the invention is susceptible ofvarious modifications andalternative constructions, I have shown in the drawings and will hereindescribe in detail the preferred embodiment, but it is to be understoodthat I do not thereby intend to limit the invention to the specific formdisclosed, but intend to cover all modifications and alternativeconstructions falling within the spirit and scope of the invention asexpressed in the appended claims.

Referring now to the drawings, Figure l shows a magnetic frictionelement constituting an armature for the annular magnet disclosed inFig. 2, each of these element-s being constructed with a gap interposedin its magnetic flux path which is indicated in dotted outline. It willbe understood that for any two cooperating elements only onenon-magnetic gap need be provided and that this may be located either inthe armature or in the magnet core. For convenience of explanation thepresent method will be described with reference to the formation of thegap in the armature ring.

In constructing the annular armature two rings 6 and 7 of magnetic ironare formed of such diameters that the smaller will fit loosely withinthe larger ring. That is to say there is a gap left between the twoelements when arranged in concentric relation, the radial width of whichgap is slightly less than the width of the non-magnetic gap to beformed. In the present type of magnet a gap of .O03 inch has been foundto be wide enough to substantially eliminate the residual magnetismwhich would otherwise tend to develop.

An adhering coating 8 of non-magnetic material is then deposited on theouter pe- Vi/'hleithe'coating may be magneticr ripheral: surface of thevrsmaller Y ring or r on the innersurface ofthe larger ring; V'This'.may be'raccomplished inany preferred inan- Y jner suchfas by the wellknown Schoop proc-V essof metal kspraying or the layer may bedepositedebyy electro plating; lig..f2 yillustrates the manner. ofapplying: the coating v l by the Schoopprocessto the external pe-f -lriphery vof the inner ring 6. To. this end a" nozzle Qis directed towardvthe VVsurface tok j be coatedandhydrogen and `oxygen' streams arecaused to lowunderpressurethrough the passagewaysvgl() inthe 'nozzlefTheseH jgases ignite withinthe y nozzle and serye/toV melt andatomizemetalsuch as brass trom a Y rodllwhich visnfed throughthecenterof the nozzle The finelyldiyided molten particles, thus projectedat high Velocityagainst the'surface of the ring,:.congeal onk the sui'-Vfaceand :unitewith each other to torin'the tenaciously;:adheringcoating. Y y: formed at a plurality of annularly spaced points aroundthey ring it is preferred tojcoat the'. entire inner surface withala-yer of uniform thickerness; Thismay` be accomplishedby rotating.

the ringrelative to the nozzle at a uni-torni rate, thepthickness of.the coating being de termined by the ratefoffsrelatire inotioirbe#l :5ztween the spray nozzle andthe ring surface. v:After depositing thenonemagnetic coat ing the two rings ,6 and. Tmay be torcedrto-` getherby the 'application of axialV pressure or the outer ring may be shrunkby thermal 3i' contraction onto'the inner; ring. In' the latter casiethering 7 is expanded by heat to a point atfwhich itzwill receivetthe innerringr 6. When thus assembled' witligtheir surfaces l2 in acommon plane,the ringsareallowed to cool,- the contraction of the outer one pro-V 1ducing a tight lit between them and produc--4 inga'n extremelyrigidstructure of the'inageV neticel'ement as'alwhole. I Y

.To VVsecurely lock theV vtwo rings .together against possible relativerotation Vwhen en# vgaging a ycoactingfmagnetic'.element under; vhighaxialpressure suitable ,keysl lof'nonmagnetic material niayabe employedLThese may Vvbe'fornied by drilling holes in the magnetic element atthejunctionbetween the two rings@ These holeseare then'plugged with ifnon-magnetic material: suoli as bronze so as, y

topreserve the non;magneticl gap between the rings.' ZVVhen bronze isused .it maybe melted a n Y l c I claim asmyinvention:

n l The method offorming'anannularmagnet-ic element which consistsin'constructingV two rings ofm'agn'etic 'inaterialladapted to iit onewithin` the other, :depositing an 'adhere v formed by the two rings.

'erVbetiiveentliemf-, y .Y l 5. The method of forming anannularmag-.fffnetic elementwhich consists `in constructing two rings of magneticmaterial adapted to litv -ing'coating of non-magnetic material on the Yperipheral surface of one ofi-*said rings, and" vassemblingthe` ringswith said coating bef" `rtween them.`v`

2. The method ofrforininganlannular magone withinthe other, coatingportions of the peripheral surface of one of said rings with f'. anadheringlayer ofnon-magnetic material,y and assembling thejftwo fringsso `that said llayerormsma gap o'lgiixed reluctanceV in thev "10Fnetidelemente-which consistsz'inponstructing ltwofringsofl-magneticmaterialadapted to fit magneticfiiu-X path?throughYthekr elementf- 3. Themetliod offfo'rming an annular mageneticelementwhich consists in4 constructing tworingsipf'magneticfmaterialadaptedztolit joiie withinithe'other,lformingr an adhering p Y 'knonfmagnetic layer on theperipheral surface,e Y

of one of-said rings by depositing `non-magj 'netic metal thereon, vandassembling the twol 'Y epfl' ringswith: said layer at the pointofjjunction between the rings'.

' K f 4. VThe method of forming aiinu'larmagr Yy netic element ywhichconsists in constructing` two rings of magnetic material1 adapted to'fitone within theother,V depositing a layer'of i nonmagneticmetalon theperipheral-surface n* *Y of one of'said rings by spraying'molten atomi'izedA metal yunder pressure against said sur! face, vand assemblingsaid-.rings one 4within thegother, coatin'gportions of theperipheralsurface ofone of said rings with an adhering layerofnonfinagnetic material,

and shrinking the larger ringiby thermal conf Y i Y traction onto thesmaller ringwith said layer l between them- The method'oforminganvaiinular mag- 'i netic elementi, which consists inyconstructingl two rings of magnetic material adapted to'fit one withinthe other, coating portions of the peripheral surface of one' of saidrings with an adheringlayer offnon-magnetic n'iaterial,y

fittingfthe two rings together vwith said layer 'betweenthem7 and keyingthe twofrings'to-y 'f gether. v

IIn testimony rwhereo'i",`r l have hereunto af'-V iXed my signature.

ARTHUR n wARNER

